35 Days to maturity. Brassica juncea var. foliosa. Hatakena Mustard Seeds. Non-GMO, Cool season annual, Heirloom. This variety of Japanese mustard is bright green in color. Its leaves are hairy with slender stems and petioles. The pungency of this mustard increases as the plant size increases. Because these types of mustard often bolt in the spring due to low dropping temperatures, or mid-summer due to high temps, it is recommended to plant by seed in the late spring/early summer, or the late summer for a fall harvest. Approx 10,000 seeds / oz.